US scientists have discovered a woman with a rare brain disease that makes her afraid of nothing.

She's not afraid of a huge snake lurking near her children, or a knife to her throat — and she's certainly not afraid of a horror movie.

The woman cannot experience fear because of a condition that has destroyed the part of her brain — the amygdala — where researchers say they believe the feeling of fear is made.

Over the past two decades researchers have been analysing the woman, known as SM, for clues about her condition which they say could help them treat post-traumatic stress disorder, particularly in soldiers returning from war.

"It is quite remarkable that she is still alive," said lead author Justin Feinstein whose study appears in the journal Current Biology.

"The nature of fear is survival and the amygdala helps us stay alive by avoiding situations, people, or objects that put our life in danger," he said.

"Because SM is missing her amygdala, she is also missing the ability to detect and avoid danger in the world."

Reminds me of something I read in a biography of Vladimir Putin. It was while studying at the Leningrad KGB intelligence school that Putin was almost given a failing grade due to the fact he had "a significantly diminished sense of fear and danger"...which could make him more reckless than his handlers might have preferred.

Note to self- never share a foxhole with anyone braver or dumber than you, never sleep with anyone crazier than you.

Friend was a Black Hat (instructor at Jump School) had kid that stepped up to the door on the 34 ft tower and jumped- without being hooked up. Bernie was working with students at the right door, did not see the kid step up to the LEFT door. When Bernie said GO, he went.

We tried to keep the fearless ones around as point man when first entering a bar that had no windows and one door.

Here's some fascinating research on the physiology of SF trainees and PTSD conducted at Fort Bragg, suggesting that successful candidates may be neurologically different from the rest of us:

Quote:

One of the most significant findings was with a peptide called “Neuropeptide Y.” It is a substance that, in addition to many other actions, works on the prefrontal cortex of the brain and helps you stay focused on a task even under stress. We found that the Special Forces trainees—the Green Berets—produced significantly more NPY than the Rangers and Marines who were going through the same training. Twenty-four hours after completing the training, the Green Beret trainees were back to baseline levels of NPY while the others were significantly depleted. In fact, there was a direct positive relationship between the amount of NPY and performance in the training. There also was a clear, negative relationship between performance scores and the number of dissociative symptoms reported by the trainees and [a negative relationship] between NPY and dissociation. In other words, the less NPY soldiers had, the more they dissociated, and the more they dissociated, the worse they did in their training.

We were very excited by these results! They suggest that at least some of the physiological factors predate the development of PTSD, that people who release high levels of NPY under stress stay mentally focused. They don’t have as many symptoms of dissociation, and at the end they bounce right back to where they started. Others, those that produce less NPY, performed very poorly in the training and looked a lot more anxious and frazzled at the end.

Then we looked at their trauma histories to see whether a history of childhood trauma or child abuse predicted differences when they went through training. Interestingly, those in the Green Beret units tended to have endured more child abuse but did better under stress. Trainees from the Rangers and Marines with a history of child abuse had more trouble during training. They didn’t produce as much NPY, they dissociated a lot, and they didn’t perform as well.